Digital Broadcast Receiving Tuner and Receiving Device Incorporating It

1. A digital broadcast receiving tuner comprising; a down-converting unit which directly converts a high-frequency signal into a baseband signal, or converts a high-frequency signal into an intermediate frequency signal and then further converts said intermediate frequency signal into a baseband signal; a gain-adjusting unit which adjusts a level of said high-frequency signal and/or said intermediate frequency signal in correspondence with an automatic gain control (AGC) controlling voltage supplied from an external source; an amplifier which adjusts a level of said baseband signal; and a controlling unit which controls a gain of said amplifier in response to a signal being independent of said AGC controlling voltage wherein said signal independent of said AGC controlling voltage is one that reflects frequency characteristics of a level of received signals within a receivable frequency band width and is a signal output from a versatile port of a semiconductor integrated circuit device loaded in said down-converting unit.

2. A digital broadcast receiving tuner according to claim 1 , wherein said controlling unit controls said gain of said amplifier so as to be variable continuously.

3. A digital broadcast receiving device comprising; a digital broadcast receiving tuner; a demodulator which demodulates a baseband signal output from said digital broadcast receiving tuner; an automatic gain control (AGC) controlling voltage generator which generates an AGC controlling voltage based on said baseband signal; a signal generator; a correction unit which corrects said AGC controlling voltage in correspondence with condition of a received signal; wherein said digital broadcast receiving tuner further comprises; a down-converting unit which directly converts a high-frequency signal into said baseband signal, or converts a high-frequency signal into an intermediate frequency signal and then further converts said intermediate frequency signal into said baseband signal; a gain-adjusting unit which adjusts a level of said high-frequency signal and/or said intermediate frequency signal in correspondence with said AG controlling voltage supplied from an external source; an amplifier which adjusts a level of said baseband signal; a controlling unit which controls a gain of said amplifier in response to a signal being independent of said AGC controlling voltage wherein said signal independent of said AGC controlling voltage is one that reflects frequency characteristics of a level of said received signal within a receivable frequency band width and is a signal output from a versatile port of a semiconductor integrated circuit device loaded in said down-converting unit; and wherein said signal generator generates said signal independent of said AGC controlling voltage based on said baseband signal.

4. A digital broadcast receiving device according to claim 3 , wherein said controlling unit controls said gain of said amplifier so as to be variable continuously.

5. A digital broadcast receiving tuner according to claim 1 , wherein said amplifier is downstream to both said down-converting unit and said gain-adjusting unit.

6. A digital broadcast receiving device according to claim 3 , wherein said amplifier is downstream to both said down-converting unit and said gain-adjusting unit.